Implantable medical device with feedthrough, feedthrough and method

Abstract

Feedthrough and method for making a feedthrough. The feedthrough has a ferrule forming a ferrule lumen, an electrically conductive pin extending longitudinally through at least a portion of the ferrule lumen, a filter capacitor surrounding the electrically conductive pin within the ferrule lumen, the filter capacitor having a bonding surface, and a ceramic seal positioned within the ferrule lumen directly abutting the filter capacitor sealing a space between the electrically conductive pin and the ferrule. The ceramic seal adheres to and creates an adhesive bond with the bonding surface of the capacitor and substantially inhibits fluid flow through the ferrule lumen.

1 . A feedthrough, comprising:
 a ferrule forming a ferrule lumen;   an electrically conductive pin extending longitudinally through at least a portion of said ferrule lumen;   a filter capacitor surrounding said electrically conductive pin within said ferrule lumen, said filter capacitor having a bonding surface;   a ceramic seal positioned within said ferrule lumen directly abutting said filter capacitor sealing a space between said electrically conductive pin and said ferrule;   said ceramic seal adhering to and creating an adhesive bond with said bonding surface of said capacitor and substantially inhibiting fluid flow through said ferrule lumen.   
     
     
         2 . The feedthrough of  claim 1  wherein said bonding surface of said capacitor is substantially non-metallic. 
     
     
         3 . The feedthrough of  claim 2  wherein said ceramic seal is a glass seal. 
     
     
         4 . The feedthrough of  claim 2  wherein said ceramic seal substantially covers said bonding surface of said filter capacitor abutting said ceramic seal to create said adhesive bond. 
     
     
         5 . The feedthrough of  claim 2  wherein said ceramic seal substantially covers said bonding surface by wetting out, at least in part, said bonding surface of said filter capacitor. 
     
     
         6 . The feedthrough of  claim 1  wherein said ceramic seal substantially surrounds said electrically conductive pin. 
     
     
         7 . The feedthrough of  claim 1  further comprising a preform operatively electrically coupling said capacitor to said pin. 
     
     
         8 . The feedthrough of  claim 7  wherein said preform comprises a ring of an active braze alloy. 
     
     
         9 . The feedthrough of  claim 7  wherein said preform comprises:
 a first active braze alloy ring operatively electrically coupling said filter capacitor to said electrically conductive pin, and 
 a second active braze alloy ring operatively electrically coupling said capacitor to said ferrule. 
 
     
     
         10 . The feedthrough of  claim 7  wherein said filter capacitor has a coating configured to electrically couple with said preform. 
     
     
         11 . The feedthrough of  claim 1  wherein said filter capacitor is oriented interior of said feedthrough and wherein said ceramic seal is oriented exterior of said feedthrough, relative to each other. 
     
     
         12 . An implantable medical device, comprising:
 a housing forming a plurality of feedthrough openings; and   a plurality of feedthroughs, each individually positioned within one of said feedthrough openings, each feedthrough comprising:
 a ferrule forming a ferrule lumen; 
 an electrically conductive pin extending longitudinally through at least a portion of said ferrule lumen; 
 a filter capacitor surrounding said electrically conductive pin within said ferrule lumen, said filter capacitor having a bonding surface; and 
 a ceramic seal positioned within said ferrule lumen directly abutting said filter capacitor sealing a space between said electrically conductive pin and said ferrule; 
 said ceramic seal adhering to and creating an adhesive bond with said bonding surface of said capacitor and substantially inhibiting fluid flow through said ferrule lumen. 
   
     
     
         13 . The implantable medical device as in  claim 12  wherein said plurality of feedthroughs are spaced on centers not more than 0.889 millimeters apart. 
     
     
         14 . The implantable medical device of  claim 12  wherein said bonding surface of said capacitor is substantially non-metallic. 
     
     
         15 . The implantable medical device of  claim 14  wherein said ceramic seal substantially covers said bonding surface of said filter capacitor abutting said ceramic seal to create said adhesive bond. 
     
     
         16 . The implantable medical device of  claim 14  wherein said ceramic seal substantially covers said bonding surface by wetting out, at least in part, said bonding surface of said filter capacitor. 
     
     
         17 . The implantable medical device of  claim 12  wherein said ceramic seal substantially surrounds said electrically conductive pin. 
     
     
         18 . The implantable medical device of  claim 12  further comprising a preform operatively electrically coupling said capacitor to said pin. 
     
     
         19 . A method for making a feedthrough, comprising the steps of:
 positioning an electrically conductive pin longitudinally through at least a portion of a ferrule lumen of a ferrule;   positioning a filter capacitor surrounding said electrically conductive pin within said ferrule lumen;   positioning a preform proximate said filter capacitor;   positioning a ceramic seal within said ferrule lumen and directly abutting said filter capacitor; and then   progressively increasing an ambient temperature from a first temperature at least as low as a softening temperature of said ceramic seal to a second temperature at least as high as a preform melting temperature of said preform so that said ceramic seal softens and substantially occupies said ferrule lumen between said ferrule and said electrically conductive pin before said preform melts and operatively electrically couples said filter capacitor to said electrically conductive pin.   
     
     
         20 . The method of  claim 19  wherein said bonding surface of said capacitor is substantially non-metallic.